This project develops and field tests a software/hardware assessment tool for assistive technology personnel who select appropriate control interface devices for persons who have difficulty interacting with their environment. This population includes individuals with learning, intellectual, or physical disabilities; very young persons; and/or elderly persons. The Control Interface Assessment System (CIAS) includes software to measure critical characteristics of users ability to interact with many potentially useful control interface devices such as touch keyboards and adaptive switches. Based on successful Phase I prototypes, CIAS is compatible with standard microcomputers and utilizes specially designed control interface devices: a Membrane Keyboard Simulator, Universal Assessment Switch, and Joystick Simulator. These devices are operated by the user performing a series of assessment activities under software control employing visual, auditory, and kinesthetic prompting. CIAS measures actuating force, displacement, targeting accuracy, response latency, time duration of activations, and other factors. It improves the accuracy of assessment procedures and provides objective information professionals need to make more reliable and thorough control interface assessments. Secondary advantages include reduced fatigue and strain on the person assessed and elimination of the need to purchase and work with the wide array of commercial access devices now necessary to complete an assessment.